People who smoke low-tar and low-nicotine, or "light" cigarettes thinking they will reduce their health risks may actually be less likely to kick the habit, according to research conducted by University of Pittsburgh and Harvard University. As such, light cigarette smokers increase their lifetime risk of a variety of smoking-related diseases suggests the study published online by the American Journal of Public Health.

The analysis, conducted by Hilary Tindle, M.D., M.P.H., assistant professor of medicine, University of Pittsburgh School of Medicine, while she was based at Harvard Medical School, found that of 12,285 self-reported smokers, those who used light cigarettes were about 50 percent less likely to quit smoking than those who smoked non-light cigarettes. Smoking light cigarettes was associated with reduced odds of quitting for all age groups, but this effect increased with progressing age, peaking in adults age 65 and older, who were 76 percent less likely to quit than their counterparts who smoked non-light cigarettes.

Additionally, Dr. Tindle and her collaborators, who included Saul Shiffman, Ph.D., professor of psychology at the University of Pittsburgh, found that more than a third (37 percent) of the self-reported smokers said they used light cigarettes to reduce their health risks. The majority of these light cigarette smokers were female, Caucasian and highly educated. The responses were obtained as part of the 2000 National Health Interview Survey, an ongoing household survey of the U.S. population conducted by the United States Census Bureau for the National Center for Health Statistics.

According to Dr. Tindle, these findings are particularly disturbing because they translate into more than 30 million U.S. adult smokers who think they are reducing their smoking-related health risks by using light cigarettes but who, in fact, actually may be increasing such risks.

"Even though smokers may hope to reduce their health risks by smoking lights, the results suggest they are doing just the opposite because they are significantly reducing their chances of quitting. Moreover, as they get older their chances of quitting become more and more diminished," Dr. Tindle said.

Light cigarettes were first introduced to the U.S. market in the late 1960s and now account for almost 90 percent of the cigarettes sold in the United States. A number of studies have refuted the notion that they have less tar and nicotine than regular cigarettes, instead suggesting that the amounts of tar and nicotine are comparable. Furthermore, research has suggested that light cigarette smokers experience little or no long-term reduction in their risk of tobacco-related disease compared to smokers of regular cigarettes.

In the article, Dr. Tindle and her coauthors suggest that physicians and other clinicians should warn their patients about light cigarettes during routine smoking cessation counseling, because research shows that smokers are more likely to show interest in quitting if they know that lights do not reduce health risks. In addition, the authors suggest that there be disclosures on cigarette packs and warnings in advertisements whenever the term "light" or similarly misleading terms are used.

"Because smoking is such a major cause of death and disability in this country and worldwide, we believe that it is critical to give smokers accurate information on the potentially detrimental effects of the use of lights to reduce health risks and the potential impact on subsequent smoking cessation," she said.

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In addition to Drs. Tindle and Schiffman, others involved in the study include Nancy A. Rigotti, M.D., and Roger B. Davis, Sc.D., Harvard Medical School; and Elizabeth M. Barbeau, Sc.D., M.P.H., and Ichiro Kawachi, M.D., Ph.D., Harvard School of Public Health. The study was funded by the Harvard Medical School's Osher Institute.

The University of Pittsburgh School of Medicine is considered among the nation's leading medical schools, renowned for its curriculum that emphasizes both the science and humanity of medicine and its remarkable growth in National Institutes of Health (NIH) grant support, which has more than doubled since 1998. For fiscal year 2005, the University of Pittsburgh ranked 8th among schools of medicine and, together with the university and hospital affiliates, ranked 7th among educational institutions, according to preliminary data. As one of the university's six Schools of the Health Sciences, the School of Medicine is the academic partner to the University of Pittsburgh Medical Center. Their combined mission is to train tomorrow's health care specialists and biomedical scientists, engage in groundbreaking research that will advance understanding of the causes and treatments of disease and participate in the delivery of outstanding patient care.